The invention relates to a device for dewatering suspensions, such as sludge or similar materials which can be dewatered, having a plurality of rollers and two filter bands which are guided around the rollers in an S-shape and enclose the material to be dewatered between them.
It relates in particular to presses with a multitude of pressure rollers, wherein successive drying of the suspension by means of the S-shaped wrapping of the rollers by the filter bands is achieved with an increase in rollers.
Such presses are employed in multitudinous designs, they are all essentially differentiated by the relative association of the successive rollers, their diameter and type of construction and the way of guiding the bands around the rollers, in particular the size of the wrap angle of the filter bands around the individual rollers.
The suspension to be dewatered varies, depending on the area of use, and it is possible to dewater various sludges, such as communal sludge, which in turn show a more or less high degree of previous water removal. The pressing of fruits or parts of fruits is also performed with such filter presses.
In the course of this it has been shown that a certain type of press, i.e. a press with a defined roller configuration and filter band guidance, will as a rule achieve an optimal operational result, i.e. generally a maximum degree of drying with specific suspensions or with specific suspension compositions. Thus, the multitude of structural variants of such presses which are available in the marketplace as a rule also are used to achieve optimum pressing results for specific or specifically set suspensions, whose degree of pre-drying, macro-molecular structure, possibly with the addition of additives, lies within a defined range.
However, the planning and construction of specific press configurations is increasingly elaborate, and such presses are relatively expensive because of the "specialist properties" described.